title: Biplane angiography for experimental validation of computational fluid dynamic models of blood flow in artificial lungs.
abstract: This article presents an investigation into the validation of velocity fields obtained from computational fluid dynamic (CFD) models of flow through the membrane oxygenators using x-ray digital subtraction angiography (DSA). Computational fluid dynamic is a useful tool in characterizing artificial lung devices, but numerical results must be experimentally validated. We used DSA to visualize flow through a membrane oxygenator at 2 L/min using 37% glycerin at 22°C. A Siemens Artis Zee system acquired biplane x-ray images at 7.5 frames per second, after infusion of an iodinated contrast agent at a rate of 33 ml/s. A maximum cross-correlation (MCC) method was used to track the contrast perfusion through the fiber bundle. For the CFD simulations, the fiber bundle was treated as a single momentum sink according to the Ergun equation. Blood was modeled as a Newtonian fluid, with constant viscosity (3.3 cP) and density (1050 kg/m3). Although CFD results and experimental pressure measurements were in general agreement, the simulated 2 L/min perfusion did not reproduce the flow behavior seen in vitro. Simulated velocities in the fiber bundle were on average 42% lower than experimental values. These results indicate that it is insufficient to use only pressure measurements for validation of the flow field because pressure-validated CFD results can still significantly miscalculate the physical velocity field. We have shown that a clinical x-ray modality, together with a MCC tracking algorithm, can provide a nondestructive technique for acquiring experimental data useful for validation of the velocity field inside membrane oxygenators.
authors.affiliation: Center for Biomedical Engineering, University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Cameron C
authors.initials: CC
authors.lastname: Jones
authors.forename: Patrizio
authors.initials: P
authors.lastname: Capasso
authors.forename: James M
authors.initials: JM
authors.lastname: McDonough
authors.forename: Dongfang
authors.initials: D
authors.lastname: Wang
authors.forename: Kyle S
authors.initials: KS
authors.lastname: Rosenstein
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Zwischenberger
mesh_terms: D015901:Angiography, Digital Subtraction; D003198:Computer Simulation; D008955:Models, Cardiovascular; D008962:Models, Theoretical; D010107:Oxygenators, Membrane